Natural enemy defense, provisioning and oviposition site selection as maternal strategies to enhance offspring survival in a sub-social bug

摘要

The influence of maternal defense against natural enemies, maternal provisioning and oviposition site selection on offspring survival before and after hatching were examined in a semelparous pentatomid bug, Ramosiana insignis. Oviposition occurs on leaves of Schoepfia schreberi, or surrounding vegetation from which nymphs migrate to feed exclusively on S. schreberi flower buds. Oviposition is asynchronous; the mother lays additional eggs immediately prior to hatching of the core brood that rapidly consume the additional eggs. In the absence of maternal defense egg masses were more heavily parasitized, suffered ant predation and an increased prevalence of sibling cannibalism. Maternal provisioning in the form of addition eggs significantly reduced the prevalence of sibling cannibalism of core brood eggs. Migration of the core brood away from the oviposition site was also significantly higher in the absence of maternal provisioning. If not consumed, additional eggs were capable of producing viable progeny of both sexes, indicating that they were in fact marginal progeny. The average clutch size on non-host vegetation was numerically greater than clutches laid on host trees (borderline significant P = 0.058). A greater number of additional eggs were deposited with clutches laid on non-host vegetation compared to those on the host plant. Egg masses on non-host vegetation were less likely to be discovered by parasitoids, compared to those on the host tree. Overall, clutches on non-host vegetation produced one third more offspring than clutches on the host tree. We conclude that R. insignis females present a remarkable combination of maternal defense, provisioning of additional eggs and oviposition site selection as strategies to enhance offspring survival in both the egg and nymph stages.